How Scientists Are Solving Peptide Drug Delivery: From Frequent Injections to Sustained-Release Systems

This review maps the landscape of peptide drug delivery challenges and solutions. The central problem is that peptide drugs have poor bioavailability — they don't cross biological membranes well and break down quickly. While subcutaneous injection is the standard delivery method, most formulations don't provide sustained release, requiring frequent injections. The authors highlight porous silicon as a particularly promising carrier material that can hold exceptionally high peptide payloads and be tuned to release peptides slowly over time.

The authors conducted a comprehensive literature review covering peptidergic drugs currently in clinical use, parenteral delivery systems, and emerging nanotechnology approaches. They gave special emphasis to their own work developing porous silicon as a peptide delivery material, summarizing its biodegradability, biocompatibility, and payload capacity.

Peptide drugs are among the most specific and least toxic therapeutics available, but the delivery problem has limited their widespread use for decades. Every major peptide drug — from insulin to semaglutide — has had to solve the same fundamental challenge of getting the molecule into the bloodstream intact. This review provides a comprehensive overview of the technologies being developed to make peptide drugs more practical, comfortable, and effective for patients.

The peptide drug market has exploded in recent years with GLP-1 agonists alone generating tens of billions in revenue. But every peptide drug shares the same delivery challenge — getting a fragile molecule into the bloodstream in a controlled way. The delivery technologies reviewed here underpin the entire field, from once-weekly semaglutide injections to the oral formulations now in development. Advances in sustained-release systems could make peptide drugs even more convenient and accessible.

As a review from 2015, it predates several major advances in peptide delivery including the SNAC-based oral semaglutide formulation (approved 2019) and newer long-acting injectable formulations. The emphasis on porous silicon reflects the authors' own research focus, which may give it disproportionate attention relative to other emerging technologies.